A thought experiment as proof of RE

At an approximately flat location such as some of the Utah salt flats, the low-lands of Belgium/Netherlands, the Somerset levels in the UK, set up two towers as far apart as reasonable possible. Using all the modern devices available to the engineer, ensure that the towers are perfectly level, at the same elevation to each other and perfectly perpendicular to the ground. Now measure the distance between the tops of the two towers and the distance between the bases of the two. In a FE model, these distances will be the same. In a RE model, there will be a difference. The further the towers are apart and the taller they are, the more pronounced this effect will be.

There is an example of this I can think of off the top of my head, ie the Humber Suspension Bridge over the Humber estuary in the UK. The towers are not parallel, but rather about 1.5" further apart at the top as compared to the bottom to account for the Earth's curvature. How does FE explain away such an effect?

There is an example of this I can think of off the top of my head, ie the Humber Suspension Bridge over the Humber estuary in the UK. The towers are not parallel, but rather about 1.5" further apart at the top as compared to the bottom to account for the Earth's curvature. How does FE explain away such an effect?

Sorry to disappoint you, but the 36mm figure quoted is only a theoretical one.  From an email I received from the Humber Bridge authority:

The two towers are build vertical to a tangent to the earth, i.e. radial to the centre of the earth, thus, theoretically, the shape between the two towers is an inverted trapesium rather than a rectangle with the length between the bottom of the towers being 36mm less than the length at the top of the towers.
 
The gap at the base is, of course, the one that was actually "measured" with the apparent increase being a result of building the towers "vertically".
 
Regards
 
Peter Hill
General Manager & Bridgemaster

 There is another way to use these large flat areas. Take a compass and take a walk straight to the east or to the west and draw a line behind you. And after the quite long walk find a chance to fly up and observer the line you drew. In RE model it would be straight line. In FE model it would be curved line because if in FE model you walk to the east or to the west you circle the north pole.

There is another way to use these large flat areas. Take a compass and take a walk straight to the east or to the west and draw a line behind you. And after the quite long walk find a chance to fly up and observer the line you drew. In RE model it would be straight line. In FE model it would be curved line because if in FE model you walk to the east or to the west you circle the north pole.

Only on the equator.  Everywhere else on the RE would also be a circle (especially near the poles).

Ok, lets go to equator then. I guess my 3D thinking isn't so good but still, I guess that in FE model the curvature would be more easily seen than in RE model.